1.1 What type of plate boundary is forming the Hawaiian Islands? Be sure to chec

Question

1.1

What type of plate boundary is forming the Hawaiian Islands? Be sure to check the map of plate boundaries in your text!

Select one:

a. Ocean to continent convergent

b. Divergent

c. Transform

d. Ocean to ocean convergent

e. None of the above

1.2

Take some time to get comfortable with this plot... it shows key relationships between magma characteristics, such as explosivity, temperature, silica content, etc. When one is high, is the other high or low?

You will want to be confident explaining the relationship between silica content, temperature, viscosity, and gas content.

Thus, becoming familiar with this plot is key to being successful with all this week's materials! Consider these relationships as the law, after all, they are based on physics!

The beginning of the Ring of Fire video helps a ton with the concept of magma viscosity and its dependence on silica content... :)

Why is basalt (the primary rock type produced by Hawaiian volcanoes) and other mafic igneous rocks generally darker in color?

Select one:

a. The rock contains mostly high-silica (feldspar and quartz) minerals.

b. The rock contains many low silica (iron and magnesium-rich) minerals.

c. The rock contains a mixture of high-silica (felsic) and low-silica (mafic) minerals.

1.3

Volcano type is an outcome of magma composition and viscosity... Why?

Because viscous lava piles up near the vent of the volcano and runny lava flows long distances, right?

And... magma viscosity (and composition) is predicted by the type of tectonic plate that melted to form the magma.

Thus, we see that certain volcano types are characteristic of specific plate tectonic settings!

Choose the volcano type that is very broad and large in diameter, with very gently sloping sides, and formed from runny, low viscosity lava (which is also low is silica):

Select one:

a. Lava dome

b. Stratovolcano

c. Cinder cone

d. Shield volcano

1.4

Choose the narrower, taller volcano-type that is built from many steeply-inclined layers of pyroclastic deposits and lava flows:

Select one:

a. Shield volcano

b. Stratovolcano

c. Cinder cone

d. Lava dome

1.5

Recap: Why do the stratovolcanoes and shield volcanoes have different shapes? What could cause the slopes to look so different?

Select one:

a. The eruptive products contrast in chemical composition

b. The eruptive products contrast in viscosity

c. More viscous lava cools and piles up closer to the vent whereas low viscosity magma travels a good distance before cooling significantly

d. All of the above

1.6

Based on your text, what are the two basic types of volcanic eruptions?

Select one:

a. Explosive and erratic

b. Explosive and effusive

c. Erratic and effusive

1.7

Remember the significance of this plot? It is LAW. It explains the relationship (or dependence) between silica content, temperature, viscosity, and gas content.

Silica rich lava is more viscous because the molecules form long chains that tangle as it flows. It is slow and sticky.

As lava boils, the dissolved gases try to escape via bubbles... but how easily can these bubbles escape when magma is thick, slow to flow, and sticky??

The properties that influence viscosity also predict GAS CONTENT...

Thus silica content, temperature, and viscosity of the magma describe the explosiveness of the volcano where the magma resides. :)

Remember, the beginning of the Ring of Fire video helps tons with these concepts... :)

Which volcanic centers have explosive eruptions?

Select one:

a. stratovolcanoes

b. lava domes

c. fissures at divergent zones

d. shield volcanos

e. A and B

f. All of the above

1.8

Based on what you learned about viscosity early on in Ring of Fire, indicate which choice lists fluids in order of increasing viscosity.

Select one:

a. a dollop of peanut butter, small puddle of honey, small pool of water

b. a small puddle of honey, dollop of peanut butter, small pool of water

c. a small pool of water, small puddle of honey, dollop of peanut butter

1.9

Now, imagine that these fluids with varying viscosity are each carbonated (with CO2 gas like in sparkling water or cola).

Consider how each fluid’s viscosity would determine the rate at which bubbles of CO2 gas could rise to the surface of the fluid and be released into the environment.

After 24 hours of gaseous release via bubbles rising to the surface and popping, which fluid would still contain the least amount of dissolved CO2? (When CO2 escapes via bubbles, it is no longer dissolved!)

Select one:

a. a small pool of water

b. a small puddle of honey

c. a dollop of peanut butter

1.10

Recap: Why does magma viscosity predict volcano explosivity?

Select one:

a. When magma migrates upwards towards the earth's surface, it feels less pressure (due to the decrease in overburden or material above it).

b. Viscous magma is more easily expelled from the vent.

c. Viscous magma traps dissolved gases that would otherwise boil out of the fluid.

d. When the gases boil, the vapor moves lava into the air as hot ash—in the same way that an aerosol spray can disperses a fluid (e.g., hairspray).

e. Answers A and B

f. Answers C and D

1.11

All eruptive products do not have the same composition or, therefore, the same viscosity.

Lava is molten rock, so minerals it contains depend on two things: 1) the type of rock that was melted, and 2) the journey the molten rock took in order to reach Earth’s surface.

Use the Igneous Rock Identification Chart in your textbook to discover what types of eruptive products are typical for shield-type volcanos versus stratovolcanos.

Which volcanoes tend to have explosive eruptions?

Select one:

a. Those with silica-rich, high viscosity magma

b. Arc volcanoes (related to subduction zones)

c. Those with high gas content magma

d. Answers A and B

e. All of the above

Composition Rhyolitc DaciticAndesitic Silica content | 70% Basaltic 60% 50% 1100-1200°C 500 poise 05% Less explosive Eruption temperature 7500-900° C 1000°C 3 x 104 poise 2.0% Viscosity (water = 0.01 poise) | 1 × 107 poise Gas content l 5.0% "Explosiveness" More explosive Lava domes Lava flows Volcanic products Pyroclastic deposits Shield volcanoes Cinder cones Volcano types Composite volcanoes Dome complexes ©2010 Pearson Education, Inc.

Explanation / Answer

Answer 1.1

(e) None of these

explanation - Hawaii it is caused by hot spot, Hawaii island formed by the volcanism within Pacific plate.

Answer 1.3

(d) shield volcano

explanation - shield volcano is charecterized by gentle uper slopes and low viscosity of magma that alow flows easily downslope

Answer 1.4

(b) stratovolcano

explanation- steeper slopes and taller and pyroclactic materials

Answer 1.5

(d) all of above

explanation - chemical composition of magma and viscosity all are controling foctor to contol shape of volcano.

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